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Report: Not all PSUs support Haswell's low-power states

Saw this little gem today... any thoughts or opinions on how widespread an issue this might turn out to be?

Originally Posted by TechReport

Indeed, according to the guys at VR-Zone, Haswell may not play nice with some existing "bargain basement" PSUs. That's because the chip's C6/C7 power states apparently require a minimum load of 0.05 amps on the 12V2 rail. The site says not all PSUs have the appropriate circuitry to let the processor sip that little power without the system becoming "unstable" or shutting down. Current Sandy Bridge and Ivy Bridge processors suck a lot more juice—0.5 amps, to be precise—in their low-power states, and meeting that requirement supposedly requires less complex circuitry inside the PSU.

And yet again, a non-issue is blown way out of proportion by the hastily self-taught, self-proclaimed know-it-all journalists. Yay.

So this will only affect those systems whose PSUs have low load/no load protection while not having minimum load resistors present, and the problem will manifest itself as a system shutdown when said system enters a deep stand-by state, from which it has to all but reboot anyway. C6 means all RAM, all cache levels and all register states are purged, and no content is dumped onto non-volatile memory. Only the EFI boot state is kept, and that means that the startup procedure can be skipped, but OS resume will take as long as a cold boot would.

This is what makes me look snazzy for testing zero, as in zero, load ripple / regulation.
So far I've had one (1) unit that freaked out. It stayed running, but ripple was Not Good.
(This does not include the two Super Bargain PSUs)

Antec PSU C7 Support

Hi,

For Antec, the current assessment is stated below. We are working on verifying all series' & sub-series', but our PD department also has other units to test (Computex coming with a couple of launches):

- HCP Platinum
- TP Gold
- EA Platinum
- HCG M

I will also prepare some official statement as a press relelase in ~2 weeks and add confirmed series here.

I didn't see anything in that article that said motherboard manufacturers are definitely going to allow users to enable/disable C7 in the BIOS. Right now all of the Haswell boards out there for testing have beta BIOSes and none of them are horribly stable except for the Intel reference board.

That said, I do agree with Robert and would expect the motherboard manufacturers to allow the ability to enable/disable that sleep state. Otherwise there will potentially be a lot of pissed off users.